The use of symbols or labels which comprise bar codes as a means for identifying data which is used in processing items sold in the retail industry, and for other purposes as well, has been widely accepted. A particular bar code, known as the Universal Product Code (UPC), has been established as the industry standard for the grocery and other related retail industries. In a multiple bar code, such as the UPC, each decimal number or character is represented by two pairs of vertical bars and spaces within a seven-bit pattern wherein a binary one bit is represented by a dark module or bar of a predetermined width and a binary zero is represented by a light module or space. Thus, for example, the decimal or character one may be represented in the UPC code by the seven-bit pattern 0011001. In keeping with the format, the decimal one would be comprised of an initial space of a two-bit width, followed by a two-bit wide bar, another two-bit space and a one-bit wide bar. For each character or decimal of the system, there are two bars and two spaces which have a total width of seven modules or bits. The width of each of the bars or spaces which comprise a character may be one, two, three or four modules wide, so long as the sum of the bars and spaces is seven bits or modules wide.
In present day merchandise checkout systems, the use of optical scanners or readers for scanning the UPC labels on purchased merchandise items has become quite common. In the checkout systems in use today, the optical reader can take the form of a reader mechanism located in a checkout counter, or the form of a hand-held wand. In either case, the optical reader will scan the bar code pattern that forms the UPC label, and will generate signals representing the bars and spaces of the pattern for transmission to a processor which determines the character represented by the bar code pattern. The character which identifies the purchased items is then transmitted to an associated data terminal device and from there to a remote or back office processor which looks up the price of the item in a table located in the processor. The price is then transmitted back through the terminal device, where the price is printed on a receipt by a printer mechanism located in the terminal device, and then to a customer display member located adjacent to the checkout counter where the price of the item is displayed. If an error occurs due to a malfunction of the printer or if the price of the item is not listed in the price-lookup table, error signals are generated, notifying the operator to take appropriate actions to correct the situation.
Means are customarily provided for altering error signals and other signals generated by the reader, and for altering other functions of the reader. For example, due to ambient noise conditions, it may be desirable to alter the volume, frequency or duration of an audible signal indicating that an acceptable scanning operation has been performed on the symbol being scanned.
In the past, the alteration of such functions has often involved the services of an equipment technician, since such alterations customarily involved operations of some complexity, such as the changing of switch settings within the reader, or by the making of software changes, which would differ depending upon the type of reader which was attached to the system.
It would be desirable to provide a method for alteration of reader functions which is simple and effective and does not require the services of a technician for accomplishment.